1. Field of the Invention
The present invention relates to an apparatus installed in a motor vehicle, for arbitrating a plurality of control requests relating to automatic control of motion of the vehicle, which are generated from respectively different sources.
2. Description of Related Art
A type of vehicle-installed apparatus generally referred to as a VLC (vehicle longitudinal control) apparatus has been proposed, which receives acceleration control requests. Each of these specifies a requested value of acceleration of the vehicle in the longitudinal (i.e., back/front) direction of the vehicle, where the acceleration value may be positive or negative. The VLC apparatus converts such an acceleration control request to a drive control request (e.g., expressing a control value of road wheel axle torque), which is supplied to a drive control apparatus such as an engine ECU (electronic control unit) and to the braking system of the vehicle, for controlling the vehicle to effect the specified change in acceleration. Such a type of VLC apparatus is described for example in Japanese patent laid-open Nos. 2004-528217 and 2006-506270.
A vehicle equipped with such a VLC apparatus may also be equipped with a control request apparatus which (as part of its functions) issues acceleration control requests that are successively inputted to the VLC apparatus. These acceleration control requests may for example be generated to provide driving support, by being applied to automatically control the vehicle to attain an appropriate acceleration value, which is determined based on current conditions of the vehicle and its occupants.
Furthermore a such vehicle may be equipped with a plurality of control request apparatuses which concurrently transmit respective acceleration control requests. In that case it is necessary to provide a control request arbitration apparatus for arbitrating the plurality of control requests, to obtain an acceleration control request that can be supplied to the VLC apparatus.
Japanese patent publication No. 2006-297995 describes such a control request arbitration apparatus, designed to operate as part of a DSS (driving support system).
Such types of control apparatus are not limited to those which control acceleration. Vehicle speed and/or position may also be controlled.
For example an ACC (Adaptive Cruise Control) apparatus automatically controls the vehicle position, or distance from a preceding vehicle (control of position). A CC (Cruise Control) apparatus automatically maintains a desired speed (control of speed), an ASL (Automatic Speed Limitation) apparatus limits the vehicle speed (control of speed). A CA (Collision Avoidance) apparatus, as part of a safety system of the vehicle, can automatically control acceleration when necessary to avoid or mitigate a collision.
The physical quantities relating to longitudinal displacement of a vehicle are position, speed, acceleration, rate of change of acceleration (i.e., “jerk”), and torque (applied to axles of road wheels of the vehicle, for attaining a required acceleration).
Non-acceleration control requests (i.e., position or speed control requests) must be converted to corresponding acceleration control requests. Thus in the prior art, when there are a plurality of non-acceleration control request apparatuses, it has been necessary for each of these to include a control request conversion section. All of the resultant acceleration control requests from the various control request apparatuses are arbitrated by an acceleration control request arbitration section, e.g., by selecting one of these inputted control requests. Acceleration control is performed in accordance with the selected acceleration control request.
Thus, it has been necessary to provide a number of control request conversion sections equal to the total number of non-acceleration control request apparatuses. Here, “control request conversion section” signifies a module of a computer program, or a dedicated hardware circuit, which performs conversion from position values to acceleration values or from speed values to acceleration values.
For increased efficiency of design, it would be desirable to reduce the necessary number of these control request conversion sections.